1. Field of the Invention
The present invention relates to an ocular accommodative function examination apparatus for objectively examining an accommodative function of an examinee's eye.
2. Description of Related Art
When refractive power of an eye of an examinee who gazes at a target (optotype) is objectively observed (detected) with time, the refractive power exhibits fluctuation like a sine wave, called accommodative microfluctuation. This accommodative microfluctuation is separated into a high frequency component (1.0-2.3 Hz) and a low frequency component (less than 0.6 Hz). In recent years, attention has been given to that the “frequency of occurrence (spectral power) of the high frequency component” (hereinafter, HFC) of the accommodative microfluctuation has certain correlation with the degree of accommodative constriction (excessive tonic accommodation, accommodative spasm); e.g., the HFC increases as a burden (constriction) on the ciliary muscle becomes larger. Based on this point of view, there has been proposed a method for examining the degree of the accommodative constriction by examining the HFC (see “Evaluation of accommodative function by HFC of accommodative microfluctuation”, Visual Science, Vol. 22 No. 3) Because it is thought that accommodation abnormal is one of causes of asthenopia (eyestrain, eye fatigue), knowing the degree of the accommodative constriction is meaningful.